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Background Epidermal growth factor receptor (EGFR) overexpressed in colorectal cancer (CRC) is a tumor target for developing the anti-tumor theranostic agents. Cetuximab, an anti-EGFR monoclonal antibody against EGFR-positive tumors, inhibits cell proliferation and growth was labeled with radioactive 111indium (111In) in this study for diagnosing EGFR-positive CRC. The aim of this study was to evaluate the efficacy of noninvasive nuclear imaging agent 111In-cetuximab and investigate the biological distribution of 111In-cetuximab in the HCT-15-induced EGFR-positive CRC tumor xenografts. Methods We conjugated cetuximab with an isotope chelator, diethylene triamine penta acetic acid (DTPA), and consequently labeled cetuximab-DTPA with 111In and measured the labeling efficacy by an instant thin layer chromatography (iTLC). Furthermore, the 111In-cetuximab was investigated and compared for imaging small (50 mm3) and large (250 mm3) tumor of CRC xenografts, respectively. Results The conjugated ratio between cetuximab and DTPA was 1:6 measured by MALDI-TOF-MS. The better labeling concentration of cetuximab with 10 mCi of 111In was calculated and experimented as 48 μg, resulting in labeling efficacy >80% detected by iTLC. The results revealed that the 111In-cetuximab accumulated in the both sizes of tumors as a reliable noninvasive diagnostic agent, whereas the ratio of tumor to muscle in the large tumor was 7.5-fold. The biodistribution data indicated that the 111In-cetuximab bound to tumor specifically that was higher than that in other organs. Conclusion We suggested that the 111In-cetuximab was potential for early diagnosis and prognostic monitor of EGFR-positive CRC in further clinical practice.

Epidermal growth factor receptor (EGFR) overexpressed in colorectal cancer (CRC) is a tumor target for developing the anti-tumor theranostic agents. Cetuximab, an anti-EGFR monoclonal antibody against EGFR-positive tumors, inhibits cell proliferation and growth was labeled with radioactiveWe conjugated cetuximab with an isotope chelator, diethylene triamine penta acetic acid (DTPA), and consequently labeled cetuximab-DTPA withThe conjugated ratio between cetuximab and DTPA was 1:6 measured by MALDI-TOF-MS. The better labeling concentration of cetuximab with 10 mCi ofWe suggested that the

Background Hypoxia in tumor niche is one of important factors to start regeneration of blood vessels, leading to increase survival, proliferation, and invasion in cancer cells. Under hypoxia microenvironment, furthermore, steadily increased hypoxia-inducible factor-1α (HIF-1α) is observed, and can increase vascular endothelial growth factor (VEGF) expression and promote angiogenesis. Zinc protoporphyrin (ZnPP), a heme oxygenase-1 (HO-1) inhibitor, is potential to inhibit tumor proliferation and progression. However, the mechanism of ZnPP in inhibition of tumor is not completely clear. We hypothesize that ZnPP may modulate HIF-1α through inhibiting HO-1, and then inhibit angiogenesis and tumor progression. This study aimed to dissect the mechanism of ZnPP in tumor suppression. Results We observed the amount of VEGF was increased in the sera of the colorectal cancer (CRC) patients (n = 34, p